Acute kidney injury treated with renal replacement therapy and 5-year mortality after myocardial infarction-related cardiogenic shock: a nationwide population-based cohort study

Background: Myocardial infarction-related cardiogenic shock is frequently complicated by acute kidney injury. We examined the influence of acute kidney injury treated with renal replacement therapy (AKI-RRT) on risk of chronic dialysis and mortality, and assessed the role of comorbidity in patients with cardiogenic shock. Methods: In this Danish cohort study conducted during 2005-2012, we used population-based medical registries to identify patients diagnosed with first-time myocardial infarction-related cardiogenic shock and assessed their AKI-RRT status. We computed the in-hospital mortality risk and adjusted relative risk. For hospital survivors, we computed 5-year cumulative risk of chronic dialysis accounting for competing risk of death. Mortality after discharge was computed with use of Kaplan-Meier methods. We computed 5-year hazard ratios for chronic dialysis and death after discharge, comparing AKI-RRT with non-AKI-RRT patients using a propensity score-adjusted Cox regression model. Results: We identified 5079 patients with cardiogenic shock, among whom 13 % had AKI-RRT. The in-hospital mortality was 62 % for AKI-RRT patients, and 36 % for non-AKI-RRT patients. AKI-RRT remained associated with increased in-hospital mortality after adjustment for confounders (relative risk = 1.70, 95 % confidence interval (CI): 1.59-1.81). Among the 3059 hospital survivors, the 5-year risk of chronic dialysis was 11 % (95 % CI: 8-16 %) for AKI-RRT patients, and 1 % (95 % CI: 0.5-1 %) for non-AKI-RRT patients (adjusted hazard ratio: 15.9 (95 % CI: 8.7-29.3). The 5-year mortality was 43 % (95 % CI: 37-53 %) for AKI-RRT patients compared with 29 % (95 % CI: 29-31 %) for non-AKI-RRT patients. The adjusted 5-year hazard ratio for death was 1.55 (95 % CI: 1.22-1.96) for AKI-RRT patients compared with non-AKI-RRT patients. In patients with comorbidity, absolute mortality increased while relative impact of AKI-RRT on mortality decreased. Conclusion: AKI-RRT following myocardial infarction-related cardiogenic shock predicted elevated short-term mortality and long-term risk of chronic dialysis and mortality. The impact of AKI-RRT declined with increasing comorbidity suggesting that intensive treatment of AKI-RRT should be accompanied with optimized treatment of comorbidity when possible.